A novel P-N heterojunction with staggered energy level based on ZnFe2O4 decorating SnS2 nanosheet for efficient photocatalytic degradation

Decomposing organic pollutants by semiconductor photocatalyst into harmless small molecules is a promising approach to resolve the increasingly severe environmental pollution problems. However, individual ZnFe2O4 (ZFO) and SnS2 often perform inefficient photocatalytic degradation due to their low valence band position or photochemical corrosion, respectively. A P-N heterojunction of ZnFe2O4/SnS2 with staggered energy level build an internal electric field to overcome the above weaknesses. The valence band of ZFO (1.45 eV) is lower than SnS2 (2.05 eV), and conductor band of ZFO (−0.35 eV) is lower than SnS2 (0.05 eV). The heterojunction could efficiently reduce the recombination of photo-induced carriers and thus greatly promote the photocatalytic activity. The resulting ZFO/SnS2 P-N heterojunction exhibits a higher photocatalytic degradation performance to methyl orange (MO) (99%) than individual ZFO (60%). This study reveals that the bandgap position of two semiconductors in a heterostructure plays an important role in determining the photogenerated charge carriers and photocatalytic performance.